The present invention relates generally to a character reading apparatus and more specifically to an apparatus for reading a series of preprinted magnetic characters on a bank check while the check is being automatically moved through the apparatus.
In order to accurately read information off of a document such as a bank check with preprinted magnetic characters, you must move the characters past a magnetic read head in a predetermined way. This causes the read head to produce an electrical signal wave form which is used by a character recognition circuit to identify each character. Two prior art general approaches have been used to provide an apparatus which is intended to read magnetic characters off of a document.
The first approach attempts to hold the velocity of the document constant as the document moves past the read head and synchronizes its character recognition circuitry with the known velocity. As the wave form is generated the known velocity is used to divide the wave form into sections which correspond to each character. These character wave forms are then compared with stored, expected wave forms to identify each character. If for mine reason the velocity has varied, the wave forms may not match any of the expected wave forms and a particular character may not be recognized, or may be recognized incorrectly which is even worse than not recognizing it at all. To minimize this problem, typically a flywheel or other high inertial system to ensure constant velocity is used. While this is satisfactory for some applications, it requires larger more expensive drive motors, special gears, or other components which increase the costs. Also the electrical requirements are typically larger and the apparatus requires a more expensive regulated power supply. This also prevents these apparatus from being powered by a typical cash register input/output port.
In the second approach, the exact position of the check relative to time is monitored as the check moves past the read head. Therefore this approach is not concerned with variations in the speed of the check, at least to a limited extent. The information provided by monitoring the movement of the check is used to adjust the information provided by the electrical signal from the read head. This combination of information is then used to match the expected signal that would be generated if the speed had been a specific constant speed. A character recognition apparatus of this type must include an arrangement for measuring the speed of the check and an arrangement for storing and using this information to modify the information provided by the read head. These additional components again add to the expense of the apparatus. Also, the additional requirement of modifying the information from the read head requires a more powerful processing device adding still more to the costs and increasing the required processing time.
Another reason prior art character reading apparatus have power requirements larger than what is available through the typical cash register input/output port is that the document moving arrangement which they use creates a relatively large amount of friction prior to and as the document is moved through the apparatus. These frictional forces increase the load of the apparatus and therefore, the apparatus has a larger power requirement which is greater than what is available in a typical cash register input/output port.
In one typical arrangement, the drive wheel which moves the document through the apparatus is also used to engage the document against the read head. In order for this drive wheel to be able to grip the document in a way which will move the document through the apparatus, the drive wheel must exert a relatively large amount of pressure against the read head. This high pressure results in a large friction force as the drive wheel rubs against the read head prior to the document engaging the drive wheel. This large friction force causes a large initial load which requires a larger power source. Once the document engages the drive wheel, the load is reduced somewhat because the document slides more easily against the read head. However, since the frictional force is proportion to the pressure at which the document is pressed against the read head, the frictional force is still larger than it needs to be because the pressure required to grip the document is substantially greater than the minimum pressure required to engage the document against the read head.
In other prior art character reading apparatus, the drive wheel is not used to engage the document against the read head, but instead, a non-rotating torsion spring arm is positioned to hold the document against the read head as the document is moved through the apparatus. As the document moves between the read head and the non-rotating torsion arm, both the read head and the torsion arm exert a friction force in the form of drag on the document that adds to the power consumption of the overall apparatus. Therefore, the prior art apparatus using this arrangement are not able to be powered directly from a typical cash register input/output port, but instead, require an additional, more expensive power storage device which is charged by the cash register.
Another disadvantage with prior art character reading apparatus is that they typically rely on gravity to assist in the alignment of the document as it is moved through the apparatus. As mentioned above, it is critical that the characters be oriented in a predetermined way so that they move past the read head in a known orientation. Prior art character reading apparatus typically use gravity to hold the document against an edge guide thereby properly orienting the document. This approach has the disadvantage of restricting the mounting or positioning of the apparatus during its operation. For example, if an apparatus designed to be positioned horizontally is instead mounted vertically on a wall, the apparatus will not orient the check properly since gravity no longer forces the document into the proper position. In a this situation, or in any situation where there is not some method of automatically orienting the document in the proper way, the operator is required to carefully orient the document to insure the characters to be read move past the read head in the proper way.
As will be described in more detail hereinafter, a character reading apparatus designed in accordance with the present invention reduces or eliminates the problems described above by providing a low powered document moving arrangement and a self aligning feature.